Okay, this is so not cool..

Jessica_Bull@Dell.com Jessica_Bull at Dell.com
Thu Oct 16 08:19:00 CDT 2003


Generally speaking hardware RAID is faster.  But the real deciding factor is
the speed of your CPU and the load it is handling.  The amount of memory is
also a factor.  Hardware RAID operates independant of these.  The level of
performance depends on what the purpose of the system is and what is the
forcasted load increase.  In other words, it may be faster now, but will it
be in one year from now.

Since you are only considering stiping the drives, all of the following may
not apply, but here is some general info on software RAID from RedHat.

Threaded rebuild process
Kernel-based configuration
Portability of arrays between Linux machines without reconstruction
Backgrounded array reconstruction using idle system resources
Hot-swappable drive support
Automatic CPU detection to take advantage of certain CPU optimizations

Here is the hardware information.  Again, not all info may apply to
striping.

The RAID Controller has it's own processor and memory independant of the
system CPU and memory. 
The array adapter's processor simultaneously executes the array functions,
the result is true hardware multi-tasking. 
Hardware RAID is independent of the Operating System. 
Hardware arrays are also highly fault tolerant. Since the array logic is
based in hardware, software is NOT required to boot. 


Jessica


-----Original Message-----
From: kevin.mcmahon at nokia.com [mailto:kevin.mcmahon at nokia.com]
Sent: Wednesday, October 15, 2003 2:58 PM
To: linux-poweredge at dell.com
Subject: RE: Okay, this is so not cool..


Do you guys know, if I'm just doing striping and don't really care about
parity, does the hardware RAID give me a significant boost over using a
software RAID?  I'm wondering if it's worth installing RAID cards or not on
my 2650's.  

Kevin McMahon

-----Original Message-----
From: ext Jessica_Bull at dell.com [mailto:Jessica_Bull at dell.com]
Sent: Wednesday, October 15, 2003 3:28 PM
To: knuffie at xs4all.nl; nick at lunarpages.com; linux-poweredge at dell.com
Subject: RE: Okay, this is so not cool..


The PERC4/SC, DC is available for purchase and is validated with the 2650.
For sales quotes, contact your Sales Rep.

Jessica Bull

-----Original Message-----
From: Seth Mos [mailto:knuffie at xs4all.nl]
Sent: Wednesday, October 15, 2003 1:58 PM
To: Nick Nelson; linux-poweredge at dell.com
Subject: Re: Okay, this is so not cool..


At 10:45 15-10-2003 -0700, Nick Nelson wrote:
>Okay, so I'm about tired of this crashing thing, I'd like to call Dell
>right now and order a new raid card for one of these dell 2650s, right now
>I'm using PERC 3/Di with Redhat 7/8/9 (using a variety of all of the
>above.)

You have the PERC3/DC /SC or the DCL version. The DC is dual channel, SC 
single channel and DCL without battery cache.

The DCL is fine if you use write through caching instead of write back. 
This is not as fast but I am pretty sure it won't toast your server.

I don't know yet if Dell sells the PERC4/SC or /DC yet. These are a lot 
faster then the 3 versions. Not because they support the u320 bus but 
rather because they are entirely different hardware with respect to the 
PERC2 and PERC3 megaraid cards. And they still use the same megaraid driver 
which is nice.

>Anyway, I have a new machine which is at half the load of the others, yet
>the disks lock up about once every 3 days, some of the other machines
>don't lock up very often, I'm not understanding it, but I want to put the
>money into new raid cards for one of them at least, and see if that fixes
>this issue.

I faced different problems in the 2450 then which was a Perc2/Si. But we 
replaced them with a Perc2/DC after 3 months service or so and the machines 
are still humming without problems.

>Can anyone tell me exactly which raid card I am best to order, I have 3 x
>73gig SCSI drives with Raid5.

Perc4 for performance or a Perc3/DC which is older but still works.

>How much should I expect to pay, should I order from dell or go
>aftermarket?

well, the dell.nl site lists the following add-on prices with a PE600-scsi
32MB PERC 3/SC RAID Controller (channels: 1xINT, 0xEXT) (+335.00 EUR)
PERC 4/SC RAID Controller (32MB) (channels: 1xINT, 0xEXT) (+200.00 EUR)

However, the plot thickens
with a pe1600sc
32MB PERC 3/SC RAID Controller (channels: 1xINT, 0xEXT) (+480.00 EUR)
PERC 4/SC RAID Controller (32MB) (channels: 1xINT, 0xEXT) (+345.00 EUR)

No word on battery cache backup on the cards but this should give you an 
idea...not.
These prices vary per country, server etc.

>Things like this..

Make you chew on your keyboard.

--
Seth
It might just be your lucky day, if you only knew.

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